Yulki’s Home Décor shows how you can match patterns when you piece panels of fabric together to make a wide curtain. This method uses hem tape rather than pins to hold the pieces together as you sew them, which provides for a more accurate pattern match.
Click the link below to go to her tutorial:
How to join patterned fabrics when sewing curtains (with video), by Yulki’s Home Décor
[photo from Yulki’s Home Décor]